lorenz_attractor_demo.py

import netomaton as ntm
from mpl_toolkits.mplot3d import axes3d
import matplotlib.pyplot as plt
import numpy as np


if __name__ == '__main__':
    a = 10.0
    b = 8/3
    r = 28.0
    dt = 0.005

    network = ntm.Network(1)

    initial_conditions = {0: [1., 1., 1.]}


    def activity_rule(ctx):
        x, y, z = ctx.current_activity

        x_n = x + a*(y - x) * dt
        y_n = y + (r*x - y - x*z) * dt
        z_n = z + (x*y - b*z) * dt

        return x_n, y_n, z_n

    trajectory = ntm.evolve(network, initial_conditions=initial_conditions,
                            activity_rule=activity_rule, timesteps=4500)

    points = np.array(ntm.get_activities_over_time_as_list(trajectory)).squeeze(1)
    X, Y, Z = points[:, 0], points[:, 1], points[:, 2]

    fig = plt.figure()
    ax = plt.axes(projection="3d")
    ax.set_xlabel("x")
    ax.set_ylabel("y")
    ax.set_zlabel("z")

    ax.scatter(X, Y, Z, s=0.5)

    plt.show()